A known pressure sensitive sensor (load sensor) includes a viscoelastic elastomer, a permanent magnet provided on one side of the viscoelastic elastomer and a Hall device provided on the opposite side of the viscoelastic elastomer. See Patent Document 1, for instance. When a pressure (load) is applied to this pressure sensitive sensor, the viscoelastic elastomer undergoes a deformation causing a change in the relative position between the permanent magnet and the Hall device so that the pressure applied to the viscoelastic elastomer can be determined from the detection value of the Hall device. In this pressure sensitive sensor, the detection range and the detection precision of the pressure is determined by the deformation property of the viscoelastic elastomer. For instance, when the viscoelastic elastomer has a relatively low elastic modulus, the detection precision (detection sensitivity) increases owing to the increased deformation of the viscoelastic elastomer, but the detection range narrows because the deformation limit of the viscoelastic elastomer is reached with a relatively low pressure. Conversely, when the viscoelastic elastomer has a relatively high elastic modulus, the detection range widens because the deformation limit of the viscoelastic elastomer is reached only with a relatively high pressure, but the detection precision (detection sensitivity) decreases owing to the reduced deformation of the viscoelastic elastomer.
Also is known the magnetic viscoelastic elastomer which internally contains magnetic particles dispersed therein. Owing to the property of the magnetic particles to polarize in a magnetic field, the elastic modulus of the viscoelastic elastomer can be varied by changing the magnetic field that is applied to the viscoelastic elastomer. See Patent Document 2, for instance.